You know where you blew up the second Anti-Air cannon while trying to disable the Leviathan's sheild? (Off the Thorn Hollow Landing Site or whatever) Look around near the remnants of the cannon with your command visor to find a giant battery. Pick it up with your ship's grapple beam and take it back to the Galactic Federation Fuel Gel Pumping Site or whatever (where the giant golem was being restrained by fuel gel cords). Look around with your command visor until you find a place to lock onto. After placing the battery in it's holding spot, the rest should become self-explanetory =D